The Humane Society of the United States (HSUS) reports that about 40 dogs of have gone missing since November in the valley, located in the Twin Falls area of southern Idaho.

"Someone is coming around and plucking animals out of people's yards," says Lisa Kauffman, Idaho director of the HSUS. "Two purebred collies were stolen this morning. We don't have any leads."

The society has put out a $5,000 reward for information, and people are buzzing about their lost pets on social media. The problem is a tough one to track, because many people who lose pets don't go to the police.

"We have been hearing and seeing a lot of things on Facebook, but we haven't had any missing dogs reports come through us," says Lt. Dan Kennedy, of the Jermone County sheriff's office.

Kauffman says people rarely report missing pets to law enforcement. Usually, missing dogs are found dead or turn up in animal shelters.

"We are trying to tell people to fill out police reports, and make this official," says Debbie Blackwood, director of the Twin Falls Animal Shelter. "An extraordinarily high number of people are contacting us by phone or Facebook. Their dogs never turn up anywhere."

The missing dogs are all ages, sizes and breeds. A few of the dogs reported missing on Craigslist are Great Danes, German shepherds, boxers, pit bulls and golden retrievers.

Clio, a purebred Chihuahua, has been missing since Dec. 14. "All four of our dogs were in crates in the garage, and when we came back from church, he was gone," says Clio's owner, Hannah Robinson, 19, of Twin Falls.

Other reports include dogs removed from fenced-in yards or who were unhooked from chains.